Project Summary/Abstract Research Cancer is a ?disease of the genome.? Numerical and structural alterations of chromosomes are the most common feature of cancer genomes. But how they are generated and how such mutations promote tumorigenesis is a major puzzle in cancer biology. Recently, a curious pattern of chromosomal alterations called chromothripsis was discovered in cancer genomes. Chromothripsis is characterized by extensive DNA deletions and rearrangements on a single chromosome that are inferred to have been generated in a single catastrophe. Chromothripsis has been implicated in 3-5% of cancers but may play a major role in karyotype evolution during cancer development. I recently demonstrated the first biological mechanism of chromothripsis based on the entrapment of intact chromosomes into abnormal nuclear structures called micronuclei. This work was enabled by a new approach combining live-cell imaging and single-cell sequencing. With this approach, I will characterize the molecular mechanisms generating DNA damage in micronuclei and reassembling the damaged chromatid into a rearranged chromosome. I will also use this approach to study the mutational outcomes of chromosome bridges, a common type of cell division errors that are linked to gene amplifications and chromothripsis. The mechanistic studies of chromothripsis and other complex chromosomal alterations will lay the foundation for classifying chromosomal alterations in cancer and understanding their etiology. I also propose to study the functional impact of chromothripsis by combining live-cell imaging and single-cell RNA sequencing. This analysis will elucidate how chromosomal rearrangement and copy-number alterations affect gene transcription and provide insight on the roles of aneuploidy in tumorigenesis. Candidate Career Goals My long-term goal is to understand cancer at the systems level?to elucidate the molecular mechanisms relating genetic mutations and transcriptional alterations to cellular phenotypes. As an independent investigator, I want to build my research program on single-cell sequencing and cell biology. The K22 award will allow me to obtain additional training in experimental biology and transition from a computational biologist to leading a research group with both experimental and computational efforts. Environment The Dana-Farber Cancer Institute has internationally recognized research programs in the areas of cancer cell biology and cancer genomics. As an affiliated researcher of the Broad Institute, I will also have access to genome sequencing services and high-performance computing provided by the Broad Institute. I expect to obtain a faculty position in a research institution that has similar facilities and intellectual environment as DFCI. After I become an independent faculty, I will assemble an advisory committee to oversee my career development and receive informal guidance from senior colleagues and colaborators.